Luján,city and national pilgrimage site on the Luján River, in the Pampa of northern Buenos Aires province, Argentina. The city was named for the conquistador Pedro Luján, who died there (1536) in a battle with the indigenous Indians.

According to tradition, in 1630 a statue of the Virgin Mary, being transported by oxcart between churches, became stuck at what is now Luján in spite of strenuous efforts to move it. This event was taken as a sign by devout Roman Catholics that the Virgin willed she should stay there, giving reason for the establishment of a religious shrine and pilgrimage site. A commemorative chapel was built, and a settlement (declared a city in 1755) grew up around it. A neo-Gothic basilica encloses the original chapel and statue of the Virgin, whose feast day on May 21 attracts large numbers of pilgrims. Luján is also the site of the provincial Historical and Colonial Museum housed in late 18th-century public buildings. Pop. (1980 prelim.2001) 3867,919266.